Conductor insulated with fused multiple layers



March 10, 1953 PoLYAM/DE ,QEs//v (vYL cw) me/who@ www Patented Mar. 10, 1953 OFFICE CONDUCTOR INSULATED WITH FUSED MULTIPLE LAYERS Lewis A. Bonden, Arlington, N. J.

application october 13,1947, serial No. 779,494

1l Claims.

This invention Arelates to thin wall, thermoplastic synthetic resin insulated conductors, and

more particularly to insulated conductors having a spiralled layer of coding or identifying marks contained Within the primary and secondary insulating Walls, the combination thus to perform as a single compatible dielectric.

Insulated conductors of this type have widespread use as analyzer cables, low tension aircraft Wire, calculating machine circuit Wire, radio and telephone apparatus Wiring, transformer lead wire, plus many others Where identifying markers Aare essential -to permit rapid installation and especially in preformed Wire harnesses. The insulated conductor of `the present invention is particularly applicable to telephone switchboard Wires Where a great number of wires 'in coded pairs are necessary, being incorporated in cables, and must each be readily identiable.

A great variety of insulated Wires having coding markers have been utilized up tol the time of this `invention but these types have inherent disadvantages which render them not wholly satisfactory. Some of the conductors heretofore used have had markers spiralled about an insulated core and subsequently impregnated and coated with a film applied from a, solution bath or dip. The above type of Wire, now in general use, is comprised of a bare or enameled conductor with a serving of silk or cotton woven over the conductor to provide a covering as Well as a coding and then provided With a waxed or lacquered surface 4treatment to finish the product. Such a construction provides many drawbacks such as slow production rate, diiiculty in soldering ends due to the enamel coating which must be removed chemically, poor resultant physical and chemical properties of finished surface. gradual lessening of dielectric properties under ordinary moisture exposures, a limited system of marking and large finished diameters. Other types of coded insulated Wires have utilised plastic coatings alone having coloring material therein. Such Wires are limited in the marking thereof and do not possess the desired electrical, chemical and physical properties as a separate insulating Wall.

An object Aof the present invention is to provide a Wire to overcome the above mentioned difculties and to provide a satisfactory coded V vide a Vmulti-color coded wire having long life .service andstablehigh insulation resistance as compared to the conventional silk served, clellulose `acetate lacquer or Wax impregnated wire.

A further object of the invention is toplovde a wire having unlimited color-coding Vpossibility and which will permit it to be fabricated at a rapid rate.

A further object is to provide ,a coded insulated conductor having a combination of coatings cf synthetic thermoplastic resins sealing in the coding marker and which will have vgood electrical, chemical, thermal and physical properties.

Other objects Will be apparent rfrom the following detailed description when taken with fthe accompanying drawings in which:

Fig. 1 is a plan view partly in section of an insulated coded conductor provided in accordance With the present invention.

Fig. 2 is a cross sectional view of the insulated conductor, and

Fig. 3 is a plan view of several conductorsof the present invention assembled in a cable for use in switchboard installations.

Referring in detail to the drawings, ra conductor l, of copper or other suitable conductive material is covered by a primary dielectric or insulation coating Il of Va thermoplastic synthetic resin having a high volume resistivity and a loW loss factor. This primary coating should have the highest possible insulation resistance with a minimum change upon high humidity or immersion in Water. There are several Synthetic thermoplastic materials havingsome characteristics of this nature, each differing slightly, but such materials do .not have all desired Chemyical, electrical and physical characteristics,

y The primary coating lor dielectric I- may'be applied in thin-Wall'dim'ensi'on LOM-1.004) by solution coating but preferably by extrusion for which purpose a thermoplastic resin is preferable. Suitable resins for this primary coating are cellulose acetate` low molecular weight polyethylene and vinylidene chloride. Each of these substances may be used but have slightly :varying characteristics and the particular oneused is chosen to give the .most satisfactory results for a specific use. Also other similar substances may be used but must be carefully chosen.

Over the primary dielectric or coating 'I l., a coding or identifying rmarker I2 is spiralled, This marker is also a synthetic thermoplastic resin and preferably cellulose acetate, .rayon acetate, or nylon yarns. This Amarker l2 is susceptible of 4production in many different -colorsrthereby giving ka wide field of marking. lt is also fpossible vvrection of the axis. resins are in commercial production such E'. I. ""du Pont de Nemours & Co., Inc. All of these have some of the desired qualities.

to have any number of these markers I2 spiralled on the primary dielectric II so as to provide a great number of diierent color combinations with a resultant increase in the possible number of markers or coded wires. In some applications it is desirable to provide complete coverage of the primary by the markers. Such a construction is shown in Fig. l wherein markers I2, I3, I1 and I8 are4r of different colors. The marker threads should have properties compatible to that of the primary insulation I I, since both are performing under similar dielectric stress. Also in order to eliminate any need for stripping -of the insulation for soldering the thermal characteristics of the marker material should be the sameasvthe primary and secondary coatings and the secondary coating or insulation must have atv leastas high a heat deformation temperature as the primary coating and the marker material. In addition the marker threads I2 should be single ended multi-plyed mono-lament yarn, untwistedgso as vto be at as possible thereby maintaining a uniically reactive atmosphere and to resist propagan tion of fungus and corrosion.

Physically the wires must bel tough, rupture and abrasive resistant and have a high heat deformation temperature to facilitate soldering and protect the core stock from displacement during this operation. In order to provide the necessary physical and chemical properties to the insulated wire a thin transparent (.004) maximum secondary insulation I4 is applied over the marker I2. This i coating I4 may be applied by any known method but preferably by extrusion for best dielectric performance. The markers I2 and the secondary coating I4 are'applied simultaneously thus binding the properly seasoned '(dry) markerssecurely between both insulating layers. In order to see lthe identifying markers the secondary coating must be transparent and in order to lend itself readily to the coating procedure should be a thermoplastic synthetic resin. Polyamide resins more commonly known as nylon are suitable for the secondary coating since they possess the desired characteristics. Nylon is a generic term for any long-chain synthetic polymeric amide which has recurringamide groups as an integral part oi the .-m'ain` polymer chain, and which is capable'of being formed into a" filament or lm in which the structural elements are oriented in the di- Several types of polyamide Vslightly diifering characteristics, but all possess A super linear polyamide resin, heat and light stabilized is also a very satisfactory type.

' Thus it may be seen that by the combination of dielectrics selected an insulated, circuit identifying, marked or coded wire is produced having very good electrical, chemical and physical properties. The individual properties of the different coatings are enhanced by the combination of the two and the possible color combinations for circuit marking are numerous. The individual coatings and the markers comprise a combination of synthetic materials-performing asl a single insulation medium to provide in effect a single dielectric wall with additional advantages as hereinbefore set forth.

If desired the primary coating I I may be omitted where low insulation resistance is not required. In this case the coding markers I2 would be fixed on the core I0 by the transparent coating I4. Such a wire would give satisfactory performance for many uses such as in transformers and motor coil winding.

It may readily be understood that low molecular weight polyethylene resins may be used as the primary coating since these resins have excellent electrical insulation characteristics, chemical inertness, and low moisture absorption. Preferably a low molecular weight polyethylene resin having good flow characteristics should be utilized.

In Fig. 3 of the drawings there is shown a section of switchboard cable having an outer sheathing I5 enclosing manyA twisted pairs of insulated coded conductors, generally designated lpmade in accordance with the present invention. The

Yinsulated conductors can be made'with a very small overall diameter bythe teaching of this invention thus materially decreasing the outside dimension of the cable but at the same time preserving the circuit coding and all desired electrical, chemical and physical properties of the conductors.

It is possible vin accordance with the teaching of this invention to provide the conductor with an extruded film of nylon with colored nylon markers and a nal jacket of nylon. Such a construction would besatisfactory on high humidity exposure due to the fact that the solid dielectric walls are uniformly separated and the vapor transmission rate of the somewhat permeable inner nylon film would be retarded considerably by the outer lm and nylon yarn separation.

What I claim is:

l. An insulated coded electric conductor comprising an electric conductor, an extruded homogeneous primary insulating coating of a synthetic thermoplastic resin on said conductor, a spiralled circuit identifying marker of a synthetic thermoplastic resin having identifying means therein surrounding said primary coating and a transparent extruded homogeneous secondary insulation of a synthetic thermoplastic resin over said marker sealing said marker and said primary coating and forming a single dielectric and substantially single physical wall, said primary coating, said marker and said secondary insulation having compatible thermal characteristics and said secondary insulation having at least as high a heat deformation temperature as said primary .coating and said marker, thereby permitting said conductor to be soldered Without stripping said insulation.

2. An insulated coded electric conductor as claimed in claim l, wherein said marker threads comprise untwisted single ended multi-monoiilament cellulose acetateV yarn.

3. An insulated coded electric conductor as claimed in claim l; wherein said secondary insulating coating comprises a super-linear polyamide resin, heat and light stabilized plastic.

4. An insulated coded electric conductor comprising an electric conductor, a primary extruded homogeneous dielectric coating of a superlinear polyamide resin having good flow characteristics, circuit identifying markers of colored untwisted single." ended multi-mono-flament yarns of cellulose acetate plastic spiralled about said primary dielectric and substantially completely covering said primary coating, and a secondary extruded homogeneous dielectric coating of a super-linear polyamide resin, heat and light stabilized plastic over said primary dielectric and said markers, said layers forming a ysing-le dielectric and substantially single physical wall. 5. An insulated coded electric conductor 4as claimed in claim 4, wherein said markers cover a minimum of 90% of said primary dielectric.

6. An insulated coded electric conductor as claimed in claim 4, wherein said primary dielectric has thin wall dimensions betweenn.0,01 inch and .004 inch and wherein said secondary dielectric has a thin wall dimension of .004 inch maximum. .l

7. An insulated coded electric conductor comprising an electric conductor, circuit identif ng marker threads of cellulose acetate of synt tic thermoplastic resin yarns spiralled over sail41 ductor and substantially completely covering aid conductor and a transparent polyamide'` y of compatible thermal characteristics havin .at least as high heat deformation as said marker threads over said threads sealing said marker threads to said conductor and forming therewith a single physical and dielectric wall. f

8. An insulated coded electric conductor as claimed in claim '7, said spiralled marker threads comprising a plurality of diierent colored adjacent bands of said threads. Q."

9. An insulated coded electric conductoru as claimed in claim '7 wherein said primary coating comprises a super-linear polyamide resin, heat and light stabilized plastic.

10. An insulated coded electric conductor comprising an electric conductor, extruded homogeneous primary and secondary insulating coatings of a synthetic thermoplastic resin on said conductor, said secondary coating being transparent, and circuit identifying marker threads comprising a plurality of adjacent bands of` different colored synthetic thermoplastic resin threads spiralled around said core over said primary coating, substantially covering said primary coating, secured and sealed between said primary and secondary insulating coatings, said marker threads substantially completely covering said primary coating, said layers having yefempatible thermal characteristics and forming a single dielectric and substantially single physical wall.

11. An insulated coded electric conductor comprising an electric conductor, an extruded homogeneous primary insulating coating of a superlinear polyamide resin, heat and light stabilized plastic on said,k conductor, circuit identifying marker threads of cellulose-acetate yarns spiralled over said primary coating substantially completely c ing said primary coating and a transparent extruded homogeneous secondary insulating coatiw of a super-linear polyamide resin, heat ardf light stabilized plastic covering said marker threads for sealing said marker threads and said primary coating and forming therewith a single dielectric Wall of uniform characteristics'f'said primary and secondary insulating coat` s and said marker threads having compatibl hermal charcteristics. said secondary coating having at least as high a heat deformation temperature as said marker threads.

LEWIS A. BONDON.

VESEFERENCES CITED The following references are of record in the le of this patent:

UNr'rED STATES PATENTS OTHER REFERENCES A Du Pont publication, Plastics Bulletin, volume 8, 1946, page article relied upon entitled Wire Products. 

1. AN INSULATED CODED ELECTRIC CONDUCTOR COMPRISING AN ELECTRIC CONDUCTOR, AN EXTRUDED HOMOGENEOUS PRIMARY INSULATING COATING OF A SYNTHETIC THERMOPLASTIC RESIN ON SAID CONDUCTOR, A SPIRALLED CIRCUIT IDENTIFYING MARKER OF A SYNTHETIC THERMOPLASTIC RESIN HAVING IDENTIFYING MEANS THEREIN SURROUNDING SAID PRIMARY COATING AND A TRANSPARENT EXTRUDED HOMOGENEOUS SECONDARY INSULATION OF A SYNTHETIC THERMOPLASTIC RESIN OVER SAID MARKER SEALING SAID MARKER AND SAID PRIMARY COATING AND FORMING A SINGLE DIELECTRIC AND SUBSTANTIALLY SINGLE PHYSICAL WALL, SAID PRIMARY COATING SAID MARKER AND SAID SECONDARY INSULATION HAVING COMPATIBLE THERMAL CHARACTERISTICS AND SAID SECONDARY INSULATION HAVING AT LEAST AS HIGH A HEAT DEFORMATION TEMPERATURE AS SAID PRIMARY COATING AND SAID MARKER, THEREBY PERMITTING SAID CONDUCTOR TO BE SOLDERED WITHOUT STRIPPING SAID INSULATION. 